The thing is that I have 3 partitions on my computer.
/dev/sda1 Type: ntfs (size 104MB; 35MB in use) [This is Windows Loader]
/dev/sda2 Type: ntfs (size 144598MB; 64536MB in use) [Here I want to install UBUNTU]
/dev/sda3 Type: ntfs (size 105353MB; 20227MB in use) [This my backup partition I don't wan't to delete anything from here, I have all my necessary information]
So the problem is when I select "Device for boot loader installation" "/dev/sda2"
"No root file system is defined.
Please correct this from the partitioning menu."
How can I resolve this? :)